The invention relates to cellulosic membranes. Cellulosic membranes are already well known and are used for dialysis, especially hemodialysis, electrodialysis, reverse osmosis, and ultrafiltration.
Cellulose is regenerated in these cases either by saponification of cellulose acetate or by precipitation with acids, alkalies, salt solutions, or water from "cuoxam" solutions, viscose solutions, or solutions in aprotic solvents with salts, as well as from solutions in tertiary amine oxide.
West German Patent 31 36 573 teaches a method of manufacturing a membrane in which a liquid mass, consisting of a reaction product manufactured at a temperature of 8.degree. to 30.degree. C. from 100 parts by weight of cuprammonium cellulose, produced from cellulose with an average degree of polymerization of 500 to 2500, with a mixture of 1 to 40 parts by weight of an ammonium or alkali metal salt of an acrylic acid/alkyl acrylate or methacrylate copolymer, a methacrylic acid/alkyl acrylate or methacrylate copolymer and/or a partial hydrolyzate of a polyalkyl acrylate or methacrylate with 10 to 70 equivalent percent carboxylic acid groups and a number average molecular weight of 500 to 200,000, is formed into a film or foil-type structure 5 to 30 .mu. thick, and the blank thus produced is dipped for coagulation and regeneration in 5-50% sulfuric acid, after which the ammonium or alkali metal salt of the polymer is washed out of the blank by dipping it in a 0.1 to 20% aqueous solution of a strong base, whereupon fine pores are formed in the blank essentially corresponding to the molecular weight of the salt.
In this method, the added polymer does not remain in the regenerated cellulose membrane, but is washed out completely when the pores are formed.
An object of the present invention is to make available cellulosic membranes with particular properties, including improved biocompatibility with hemodialysis membranes.